DESCRIPTION Abstract This project seeks to develop a novel, multiplexed high-throughput method to measure the capacity of cells from different individuals to repair a wide variety of DNA damages, representative of damage induced by agents present in our environment, and representative of damage induced by chemotherapeutic agents. Measuring these capacities will integrate the influence of genotype across DNA repair genes and the influence of variations in the expression level for these genes. We will develop a library of expression vectors each containing a gene for a different fluorescent protein, with each gene having been engineered to contain a specific kind of DNA lesion. We will transfect a mixture of these plasmids into cells and the repair of each kind of DNA lesion will be monitored over time because it will be reported by increased expression of fluorescent protein as the DNA lesions (known to inhibit transcription) are repaired. Fluorescent imaging methods allowing repeated measurements of individual cells will be developed. The ultimate goal is to develop the methodology such that it will become a standard clinical test applied to human blood samples as a matter of routine and that it will be used to monitor DNA repair capacity in many different human cell types (e.g., bone marrow cells of cancer patients undergoing chemotherapy, as well as the cancer cells being treated). In the long term using stem cell differentiation to aid in determining DNA repair capacity for a panel of tissues from each individual could provide important information on the susceptibility of that individual to environmental exposures, or the ability of an individual to withstand the toxic side effects of radiation and chemotherapy. Public Health Relevance Throughout our lifetime we are relentlessly exposed to chemical and physical agents that cause damage to our genetic material. Many such agents are present in our natural and manmade environment, some are produced endogenously by cells, and othe